Pull-type harvesting machines are typically towed from the tractor by a hitch arm which requires to be adjusted in angle relative to the frame of the machine for fine steering movements and more coarse movement to the transport position.
Some machines are required to follow the tractor only to one side and thus include a hitch arm which is located at one end of the machine. In others in which the present invention is particularly effective, the hitch arm to the tractor extends from the frame over the header to a hitch coupling and can be swung by an operating cylinder from one side of the header to the other so that the header can be located in echelon with the tractor to one side or generally symmetrically to the other side.
Pull-type machines of this type are well known and there are many different examples manufactured by a number of different companies.
The present invention relates primarily to disk headers, otherwise known as rotary mowers, where the design is particularly applicable. However other types of headers can use the same arrangement, including sickle bar headers, where typically a reel is provided to control movement of the crop into the cutting knife.
The present invention relates primarily to headers which use a center tongue or hitch arm which can pivot to either side of a center line, including to a position at right angles to the center line for transport. A center pivot machine uses a swing cylinder to steer the machine from one field position to another and the maximum allowed swing is controlled either by the cylinder stops or separate mechanical stops between the hitch and rear frame. During field operation the operator generally steers from one stop to the other so does not need to fine tune his position very much using the cylinders. Swing angles are generally of the order of or slightly less than 45 degree range either side of the center line to help maintain machine stability.
However other types of headers can use the same arrangement, including headers where the hitch arm is located at one end and is generally fixed during normal operation but can pivot to the position at right angles to the center line for transport.
Disk headers which utilize as the cutting system a plurality of spaced disks across the width of the header with each disk rotating about a respective vertical axis are known and widely used.
Disk headers include a support frame with a main rear beam carried on a pair of spaced ground wheels with the cutter bar and conditioning system suspended from the frame.
Often such disk headers are relatively narrow in field width, such as 12 feet or 16 feet, so that transport has been carried out simply by moving the center tongue to a straight ahead position so that the header is pulled directly behind the tractor. In many jurisdictions this has been accepted even though the width of the header is still greater than the acceptable road width. However legal requirements for trailing machines on the roads are becoming more strict and users are becoming more aware of the risks of trailing over-width equipment. Also there is an increasing requirement to provide machines of greater width which is likely to become more important when the transport problem is suitable solved.
Some manufacturers therefore provide a trailer which allows the header to be carried on the trailer in a direction transverse to the forward field direction bearing in mind that the transverse width of the header is typically an acceptable transport width. However trailers are undesirable in that the trailer forms extra equipment which much be purchased, in that the trailer must be towed from place to place and therefore may often be in the wrong place or not immediately available thus increasing transport times.
Attempts have been made therefore often in Europe where transport requirements are more strict to provide transport wheels on the header which can be deployed to the ground allowing the header to be towed on the transport wheels in the transverse direction.
The provision of a transport system on the header requires the use of additional hydraulic circuits for operating the transport deployment cylinders, the frame lift system for the ground wheels and the hitch steering. However on many tractors there are limited arrangements for controlling fluid supply.